Mapping N- to C-terminal allosteric coupling through disruption of a putative CD74 activation site in D-dopachrome tautomerase.

The macrophage migration inhibitory factor (MIF) protein family consists of MIF and D-dopachrome tautomerase (also known as MIF-2). These homologs share 34% sequence identity while maintaining nearly indistinguishable tertiary and quaternary structure, which is likely a major contributor to their overlapping functions, including the binding and activation of the cluster of differentiation 74 (CD74) receptor to mediate inflammation. Previously, we investigated a novel allosteric site, Tyr99, that modulated N-terminal catalytic activity in MIF through a "pathway" of dynamically coupled residues. In a comparative study, we revealed an analogous allosteric pathway in MIF-2 despite its unique primary sequence. Disruptions of the MIF and MIF-2 N termini also diminished CD74 activation at the C terminus, though the receptor activation site is not fully defined in MIF-2. In this study, we use site-directed mutagenesis, NMR spectroscopy, molecular simulations, in vitro and in vivo biochemistry to explore the putative CD74 activation region of MIF-2 based on homology to MIF. We also confirm its reciprocal structural coupling to the MIF-2 allosteric site and N-terminal enzymatic site. Thus, we provide further insight into the CD74 activation site of MIF-2 and its allosteric coupling for immunoregulation.

Impact of severity and age with variable definitions of bronchopulmonary dysplasia on neurodevelopmental outcomes.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is associated with neurodevelopmental impairment (NDI). METHODS: To compare the ability of NICHD 2001 and Jensen 2019 definitions of BPD and respiratory support at 40 weeks postmenstrual age (PMA) to predict NDI, a retrospective study (1/2010-12/2020) was conducted in infants with gestational age <32 weeks and birth weight <1500 g. The primary outcome measure was NDI at 18-24 months corrected age. RESULTS: Of 1119 infants, 227 (20.7%) met the inclusion criteria and had adequate follow-up data. Multivariate regression analysis showed that the NICHD 2001 definition was not predictive of NDI. Infants with Grade 2 or 3 BPD (Jensen 2019) had 4.75 (95% CI: 1.282-17.563) times greater odds of having NDI than infants without BPD. Infants requiring respiratory support at 40 weeks PMA had 4.95 (95% CI: 1.490-16.47) times greater odds of having NDI. Receiver operating characteristic curves demonstrated that the 2 definitions of BPD and the need for respiratory support at 40 weeks PMA were similar in their ability to predict NDI. CONCLUSION: There is no significant difference in the ability of the NICHD 2001 and Jensen 2019 BPD definitions, as well as the need for respiratory support at 40 weeks, for predicting NDI. IMPACT STATEMENT: Current bronchopulmonary dysplasia (BPD) definitions may not effectively predict neurodevelopmental impairment (NDI) in preterm infants. Grades 2/3 BPD (Jensen 2019 criteria) significantly associate with NDI. Infants requiring respiratory support at 40 weeks post-menstrual age (PMA) have 5 times higher odds of NDI than those on room air at 40 weeks PMA. The NICHD 2001, Jensen 2019 definitions, and the requirement for respiratory support at 40 weeks PMA, do not differ in their ability to predict NDI. Future studies should include multiple centers, with level III-IV NICUs, catering to socioeconomic, culturally, and racially diverse populations.

Reticulocyte Count: The Forgotten Factor in Transfusion Decisions for Extremely Low Birth Weight Infants.

OBJECTIVE: Extremely low birth weight (ELBW) infants often receive transfusions of packed red blood cells (PRBCs). Long-term outcomes of infants treated with liberal versus restricted transfusion criteria have been evaluated with conflicting results. Clinicians incorporate a reticulocyte count (RC) in their transfusion decisions. There is a lack of information on reference ranges for RCs in growing ELBW infants and whether infant's chronologic age or corrected gestational age (GA) generates a specific trend in the RCs. Our aim was to evaluate the levels of RCs obtained from ELBW infants over the course of the initial hospitalization. STUDY DESIGN: A retrospective chart review of ELBW infants treated in the neonatal intensive care unit (NICU) and had RCs performed. We analyzed the RCs to observe trends based on the chronologic age and corrected GA. RESULTS: A total of 738 RCs were analyzed. A positive trend in RCs that reached a peak at 32 to 34 weeks' corrected GA and then experienced a downward trend was observed. CONCLUSION: Our report examines a very common hematologic test that is theoretically helpful but is in need of guidelines concerning the appropriate frequency of testing and its utility in making transfusion decisions in ELBW infants. KEY POINTS: · RCs should help in making transfusion decisions for ELBW infants.. · No current reference ranges for RC in this population.. · No current reference ranges for RC based on GA and postnatal age..

Correlation of Polymorphonuclear Cell Burden and Microbial Growth to the Inflammatory Cytokines in Tracheal Aspirates from Ventilated Preterm Infants.

OBJECTIVE: The significance of the presence of microorganisms and polymorphonuclear cells in the tracheal aspirates (TAs) of ventilated preterm infants is not well known. Our aim was to correlate information about the presence of polymorphonuclear cells with microbial growth and the cytokine milieu in the TAs of infants who have been intubated for >7 days. STUDY DESIGN: TAs were collected from infants who had been intubated for 7 days or longer. Respiratory cultures were performed, and infants were stratified based on the presence and abundance of polymorphonuclear cells and microbial growth. Cytokines were measured in the TAs of each of the respective groups. RESULTS: In the 19 infants whose TAs were collected, the presence of at least moderate WBC with presence of microbial growth was positively associated with the presence of interleukin (IL)-10, IL-1ß, IL-8, and tumor necrosis factor (TNF)-α. The presence of at least moderate WBC, with or without microbial growth, was correlated positively with the presence of IL-8 and TNF-α. CONCLUSION: There are higher levels of proinflammatory cytokines (especially, IL-10, IL-1ß, and TNF-α) in TAs with higher cell counts and presence of microbial growth. The findings suggest that the presence of microbial growth correlated with inflammatory burden and warrant a larger study to see if treatment of microbial growth can ameliorate the inflammatory burden. KEY POINTS: · Concomitant evaluation of inflammatory cells, microbial growth, and cytokines in tracheal aspirates.. · Moderate TA WBC with presence of microbial growth associated with IL-10, IL-1ß, IL-8, and TNF-α.. · Moderate TA WBC, with/without microbial growth, correlated with the presence of IL-8 and TNF-α.. · Higher levels of IL-10, IL-1ß, and TNF-α correlated with higher TA cell counts and microbial growth..

Iron Deficiency Prior to Discharge in Very Low Birth Weight Infants: Screening with Reticulocyte Hemoglobin Content.

OBJECTIVE: This study aimed to assess the iron status prior to discharge in very low birth weight (VLBW) infants utilizing reticulocyte hemoglobin content (CHr) and evaluate the impact of delayed cord clamping (DCC) on iron status. STUDY DESIGN: This is a retrospective analysis of VLBW infants from two tertiary level of care Neonatal Intensive Care Units. The primary outcome was the proportion of VLBW infants with low CHr (<29 pg) prior to discharge. Hematologic parameters were also compared between infants who received or did not receive DCC. Infants with a positive newborn screen for hemoglobin Bart's were excluded. RESULTS: Among the 315 infants included, 99 infants (31.4%) had low CHr prior to discharge. The median (interquartile range) CHr prior to discharge was 30.8 pg (28.4-39 pg). DCC was performed in 46.7% of infants. Hemoglobin at birth, discharge, and CHr prior to discharge were higher and the need for blood transfusion and the number of infants with low CHr prior to discharge were lower in the DCC group. CONCLUSION: Approximately 31.4% of VLBW infants had low CHr near the time of discharge suggesting they were iron deficient. DCC improved hematological parameters prior to discharge in VLBW infants. CHr content can be used to guide iron supplementation in VLBW infants to potentially improve their iron status and long-term neurocognitive outcomes. KEY POINTS: · DCC was associated with an improved hemoglobin and iron status at discharge in VLBW infants.. · CHr is an early and reliable marker for iron deficiency.. · Approximately one in three VLBW infants can be iron deficient at the time of discharge..

A structurally preserved allosteric site in the MIF superfamily affects enzymatic activity and CD74 activation in D-dopachrome tautomerase.

The macrophage migration inhibitory factor (MIF) family of cytokines contains multiple ligand-binding sites and mediates immunomodulatory processes through an undefined mechanism(s). Previously, we reported a dynamic relay connecting the MIF catalytic site to an allosteric site at its solvent channel. Despite structural and functional similarity, the MIF homolog D-dopachrome tautomerase (also called MIF-2) has low sequence identity (35%), prompting the question of whether this dynamic regulatory network is conserved. Here, we establish the structural basis of an allosteric site in MIF-2, showing with solution NMR that dynamic communication is preserved in MIF-2 despite differences in the primary sequence. X-ray crystallography and NMR detail the structural consequences of perturbing residues in this pathway, which include conformational changes surrounding the allosteric site, despite global preservation of the MIF-2 fold. Molecular simulations reveal MIF-2 to contain a comparable hydrogen bond network to that of MIF, which was previously hypothesized to influence catalytic activity by modulating the strength of allosteric coupling. Disruption of the allosteric relay by mutagenesis also attenuates MIF-2 enzymatic activity in vitro and the activation of the cluster of differentiation 74 receptor in vivo, highlighting a conserved point of control for nonoverlapping functions in the MIF superfamily.

Moving bronchopulmonary dysplasia research from the bedside to the bench.

Although advances in the respiratory management of extremely preterm infants have led to improvements in survival, this progress has not yet extended to a reduction in the incidence of bronchopulmonary dysplasia (BPD). BPD is a complex multifactorial condition that primarily occurs due to disturbances in the regulation of normal pulmonary airspace and vascular development. Preterm birth and exposure to invasive mechanical ventilation also compromises large airway development, leading to significant morbidity and mortality. Although both predisposing and protective genetic and environmental factors have been frequently described in the clinical literature, these findings have had limited impact on the development of effective therapeutic strategies. This gap is likely because the molecular pathways that underlie these observations are yet not fully understood, limiting the ability of researchers to identify novel treatments that can preserve normal lung development and/or enhance cellular repair mechanisms. In this review article, we will outline various well-established clinical observations while identifying key knowledge gaps that need to be filled with carefully designed preclinical experiments. We will address these issues by discussing controversial topics in the pathophysiology, the pathology, and the treatment of BPD, including an evaluation of existing animal models that have been used to answer important questions.

Adiponectin ameliorates hyperoxia-induced lung endothelial dysfunction and promotes angiogenesis in neonatal mice.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a common respiratory disease of preterm infants. Lower circulatory/intrapulmonary levels of the adipokine, adiponectin (APN), occur in premature and small-for-gestational-age infants and at saccular/alveolar stages of lung development in the newborn rat. However, the role of low intrapulmonary APN during hyperoxia exposure in developing lungs is unknown. METHODS: We test the hypothesis that treatment of hyperoxia-exposed newborn mice with recombinant APN protein attenuates the BPD phenotype characterized by inflammation, impaired alveolarization, and dysregulated vascularization. We used developmentally appropriate in vitro and in vivo BPD modeling systems as well as human lung tissue. RESULTS: We observed reduced levels of intrapulmonary APN in experimental BPD mice and human BPD lungs. APN-deficient (APN-/-) newborn mice exposed to moderate (60% O2) hyperoxia showed a worse BPD pulmonary phenotype (inflammation, enhanced endothelial dysfunction, impaired pulmonary vasculature, and alveolar simplification) as compared to wild-type (WT) mice. Treatment of hyperoxia-exposed newborn WT mice with recombinant APN protein attenuated the BPD phenotype (diminished inflammation, decreased pulmonary vascular injury, and improved pulmonary alveolarization) and improved pulmonary function tests. CONCLUSIONS: Low intrapulmonary APN is associated with disruption of lung development during hyperoxia exposure, while recombinant APN protein attenuates the BPD pulmonary phenotype. IMPACT: Intrapulmonary APN levels were significantly decreased in lungs of experimental BPD mice and human BPD lung tissue at various stages of BPD development. Correlative data from human lung samples with decreased APN levels were associated with increased lung adhesion markers (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin). Decreased APN levels were associated with endothelial dysfunction and moderate BPD phenotype in APN-deficient, as compared to WT, experimental BPD mice. WT experimental BPD mice treated with recombinant APN protein had an improved pulmonary structural and functional phenotype. Exogenous APN may be considered as a potential therapeutic agent to prevent BPD.

Delayed Cord Clamping for 45 Seconds in Very Low Birth Weight Infants: Impact on Hemoglobin at Birth and Close to Discharge.

OBJECTIVE: To assess the impact of delayed cord clamping (DCC) for 45 seconds on hemoglobin at birth and close to discharge in very low birth weight (VLBW) infants and to compare modes of delivery in infants who received DCC. STUDY DESIGN: In a retrospective study, 888 VLBW infants (≤1,500 g) who survived to discharge and received immediate cord clamping (ICC) were compared with infants who received DCC. Infants who received DCC and born via Cesarean section (C-section) were compared with those born via vaginal birth. RESULTS: A total of 555 infants received ICC and 333 DCC. Only 188 out of 333 VLBW infants (56.5%) born during the DCC period received DCC. DCC was associated with higher hemoglobin at birth (15.9 vs. 14.9 g/dL, p = 0.001) and close to discharge (10.7 vs. 10.1 g/dL, p < 0.001) and reduced need for blood transfusion (39.4 vs. 54.9%, p < 0.001). In the DCC group, hemoglobin at birth and close to discharge was similar in infants born via C-section and vaginal birth. CONCLUSION: DCC for 45 seconds increased hemoglobin at birth and close to discharge and reduced need for blood transfusion in VLBW infants. DCC for 45 seconds was equally effective for infants born by C-section and vaginal delivery. Approximately 44% of VLBW infants did not receive DCC even after implementing DCC guidelines. KEY POINTS: · Studies to date have shown that DCC improves mortality and short- and long-term outcomes in VLBW infants.. · No consistent guidelines for the duration of DCC in preterm and term neonates.. · DCC for 45 seconds increased hemoglobin at birth and close to discharge in VLBW infants..

miR34a: a novel small molecule regulator with a big role in bronchopulmonary dysplasia.

Preterm infants with bronchopulmonary dysplasia (BPD), characterized by pulmonary inflammation leading to impaired alveolarization and vascular dysregulation, have an increased risk of abnormal lung function in infancy, childhood, and adulthood. These include a heightened risk of pulmonary hypertension, and respiratory illnesses. MicroRNAs (miRNAs) are known to disrupt normal lung development and function by interrupting alveolarization and vascularization resulting in the development of BPD. Among the various miRs involved in BPD, miR34a has been shown to have a significant role in BPD pathogenesis. Targeting miR34a or its downstream targets may be a promising therapeutic intervention for BPD. In this review, we summarize the data on cellular arrest, proliferation, differentiation, epithelial-mesenchymal transition, mitochondrial dysfunction, and apoptosis impacted by miR34a in the development of BPD pulmonary phenotypes while predicting the future perspective of miR34a in BPD.

α1,3-Fucosyltransferase-IX, an enzyme of pulmonary endogenous lung stem cell marker SSEA-1, alleviates experimental bronchopulmonary dysplasia.

BACKGROUND: Endogenous pulmonary stem cells (PSCs) play an important role in lung development and repair; however, little is known about their role in bronchopulmonary dysplasia (BPD). We hypothesize that an endogenous PSC marker stage-specific embryonic antigen-1 (SSEA-1) and its enzyme, α1,3-fucosyltransferase IX (FUT9) play an important role in decreasing inflammation and restoring lung structure in experimental BPD. METHODS: We studied the expression of SSEA-1, and its enzyme FUT9, in wild-type (WT) C57BL/6 mice, in room air and hyperoxia. Effects of intraperitoneal administration of recombinant human FUT9 (rhFUT9) on lung airway and parenchymal inflammation, alveolarization, and apoptosis were evaluated. RESULTS: On hyperoxia exposure, SSEA-1 significantly decreased at postnatal day 14 in hyperoxia-exposed BPD mice, accompanied by a decrease in FUT9. BPD and respiratory distress syndrome (RDS) in human lungs showed decreased expression of SSEA-1 as compared to their term controls. Importantly, intraperitoneal administration of FUT9 in the neonatal BPD mouse model resulted in significant decrease in pulmonary airway (but not lung parenchymal) inflammation, alveolar-capillary leakage, alveolar simplification, and cell death in the hyperoxia-exposed BPD mice. CONCLUSIONS: An important role of endogenous PSC marker SSEA-1 and its enzyme FUT9 is demonstrated, indicating early systemic intervention with FUT9 as a potential therapeutic option for BPD. IMPACT: Administration of rhFUT9, an enzyme of endogenous stem cell marker SSEA-1, reduces pulmonary airway (but not lung parenchymal) inflammation, alveolar-capillary leak and cell death in the BPD mouse model. SSEA-1 is reported for the first time in experimental BPD models, and in human RDS and BPD. rhFUT9 treatment ameliorates hyperoxia-induced lung injury in a developmentally appropriate BPD mouse model. Our results have translational potential as a therapeutic modality for BPD in the developing lung.

Antenatal N-acetylcysteine to improve outcomes of premature infants with intra-amniotic infection and inflammation (Triple I): randomized clinical trial.

BACKGROUND: Intrauterine infection and/or inflammation (Triple I) is an important cause of preterm birth (PTB) and adverse newborn outcomes. N-acetylcysteine (NAC) is a Food and Drug Administration (FDA)-approved drug safely administered to pregnant women with acetaminophen toxicity. METHODS: We conducted a single-center, quadruple-blind, placebo-controlled trial of pregnant women with impending PTB due to confirmed Triple I. Participants (n = 67) were randomized to an intravenous infusion of NAC or placebo mimicking the FDA-approved regimen. Outcomes included clinical measures and mechanistic biomarkers. RESULTS: Newborns exposed to NAC (n = 33) had significantly improved status at birth and required less intensive resuscitation compared to placebo (n = 34). Fewer NAC-exposed newborns developed two or more prematurity-related severe morbidities [NAC: 21% vs. placebo: 47%, relative risk, 0.45; 95% confidence interval (CI) 0.21-0.95] with the strongest protection afforded against bronchopulmonary dysplasia (BPD, NAC: 3% vs. placebo: 32%, relative risk, 0.10; 95% CI: 0.01-0.73). These effects were independent of gestational age, birth weight, sex, or race. Umbilical cord plasma NAC concentration correlated directly with cysteine, but not with plasma or whole blood glutathione. NAC reduced the placental expression of histone deacetylase-2, suggesting that epigenetic mechanisms may be involved. CONCLUSIONS: These data provide support for larger studies of intrapartum NAC to reduce prematurity-related morbidity. IMPACT: In this randomized clinical trial of 65 women and their infants, maternal intravenous NAC employing the FDA-approved dosing protocol resulted in lower composite neonatal morbidity independent of gestational age, race, sex, and birthweight. Administration of NAC in amniocentesis-confirmed Triple I resulted in a remarkably lower incidence of BPD. As prior studies have not shown a benefit of postnatal NAC in ventilated infants, our trial highlights the critical antenatal timing of NAC administration. Repurposing of NAC for intrapartum administration should be explored in larger clinical trials as a strategy to improve prematurity-related outcomes and decrease the incidence of BPD.

Respiratory Complications in Infants with Retinopathy of Prematurity (ROP) Requiring Laser Photocoagulation.

OBJECTIVE: The objective of this paper was to describe peri-procedural events and complications of infants requiring laser photocoagulation for retinopathy of prematurity (ROP) in a level IV neonatal intensive care unit. STUDY DESIGN: A retrospective chart review was performed of neonates requiring ROP exams from January 2017 to August 2020. Baseline maternal and neonatal characteristics, ROP exam findings, and associated treatment were analyzed. Group characteristics were compared based on the need for laser photocoagulation. Subgroup analysis of the laser group including respiratory outcomes, cardiorespiratory index (CRI) scores, and pain scores was also performed. RESULTS: Neonatal and maternal characteristics in the laser (n = 27) and non-laser (n = 172) groups were assessed. Of the 81.5% (22/27) that required re-intubation for laser, 36% (8/22) had >1 intubation and 18% (4/22) had >1 extubation attempt. The average duration of intubation following laser was 2.46 ± 7.13 days, with 40% (9/22) needing peri-extubation steroids and 18% (4/22) racemic epinephrine to facilitate extubation. Mean total respiratory support time post-laser was 8.65 ± 15.23 days. Mean neonatal pain, agitation, and sedation scores after laser were zero immediately after the procedure, 0.09 ± 0.33 at 12 hours, 0.11 ± 0.47 at 24 hours, and 0.11 ± 0.51 at 48 hours. The mean CRI scores were 1 ± 0 immediately after the procedure, 1.17 ± 0.4 at 12 hours, 1.41 ± 0.20 at 24 hours, and 1 ± 0 at 48 hours. CONCLUSION: Nearly all infants undergoing laser photocoagulation for ROP in our cohort required intubation and continued respiratory support. Despite stability during the procedure, complications from intubation were common. KEY POINTS: · Routine intubation for laser is associated with complications.. · Need for post-procedural respiratory support is common.. · Avoiding intubation may mitigate these neonatal complications..

Small Immunomodulatory Molecules as Potential Therapeutics in Experimental Murine Models of Acute Lung Injury (ALI)/Acute Respiratory Distress Syndrome (ARDS).

BACKGROUND: Acute lung injury (ALI) or its most advanced form, acute respiratory distress syndrome (ARDS) is a severe inflammatory pulmonary process triggered by a variety of insults including sepsis, viral or bacterial pneumonia, and mechanical ventilator-induced trauma. Currently, there are no effective therapies available for ARDS. We have recently reported that a novel small molecule AVR-25 derived from chitin molecule (a long-chain polymer of N-acetylglucosamine) showed anti-inflammatory effects in the lungs. The goal of this study was to determine the efficacy of two chitin-derived compounds, AVR-25 and AVR-48, in multiple mouse models of ALI/ARDS. We further determined the safety and pharmacokinetic (PK) profile of the lead compound AVR-48 in rats. METHODS: ALI in mice was induced by intratracheal instillation of a single dose of lipopolysaccharide (LPS; 100 µg) for 24 h or exposed to hyperoxia (100% oxygen) for 48 h or undergoing cecal ligation and puncture (CLP) procedure and observation for 10 days. RESULTS: Both chitin derivatives, AVR-25 and AVR-48, showed decreased neutrophil recruitment and reduced inflammation in the lungs of ALI mice. Further, AVR-25 and AVR-48 mediated diminished lung inflammation was associated with reduced expression of lung adhesion molecules with improvement in pulmonary endothelial barrier function, pulmonary edema, and lung injury. Consistent with these results, CLP-induced sepsis mice treated with AVR-48 showed a significant increase in survival of the mice (80%) and improved lung histopathology in the treated CLP group. AVR-48, the lead chitin derivative compound, demonstrated a good safety profile. CONCLUSION: Both AVR-25 and AVR-48 demonstrate the potential to be developed as therapeutic agents to treat ALI/ARDS.

Chitin-Derived AVR-48 Prevents Experimental Bronchopulmonary Dysplasia (BPD) and BPD-Associated Pulmonary Hypertension in Newborn Mice.

Bronchopulmonary dysplasia (BPD) is the most common complication of prematurity and a key contributor to the large health care burden associated with prematurity, longer hospital stays, higher hospital costs, and frequent re-hospitalizations of affected patients through the first year of life and increased resource utilization throughout childhood. This disease is associated with abnormal pulmonary function that may lead to BPD-associated pulmonary hypertension (PH), a major contributor to neonatal mortality and morbidity. In the absence of any definitive treatment options, this life-threatening disease is associated with high resource utilization during and after neonatal intensive care unit (NICU) stay. The goal of this study was to test the safety and efficacy of a small molecule derivative of chitin, AVR-48, as prophylactic therapy for preventing experimental BPD in a mouse model. Two doses of AVR-48 were delivered either intranasally (0.11 mg/kg), intraperitoneally (10 mg/kg), or intravenously (IV) (10 mg/kg) to newborn mouse pups on postnatal day (P)2 and P4. The outcomes were assessed by measuring total inflammatory cells in the broncho-alveolar lavage fluid (BALF), chord length, septal thickness, and radial alveolar counts of the alveoli, Fulton's Index (for PH), cell proliferation and cell death by immunostaining, and markers of inflammation by Western blotting and ELISA. The bioavailability and safety of the drug were assessed by pharmacokinetic and toxicity studies in both neonatal mice and rat pups (P3-P5). Following AVR-48 treatment, alveolar simplification was improved, as evident from chord length, septal thickness, and radial alveolar counts; total inflammatory cells were decreased in the BALF; Fulton's Index was decreased and lung inflammation and cell death were decreased, while angiogenesis and cell proliferation were increased. AVR-48 was found to be safe and the no-observed-adverse-effect level (NOAEL) in rat pups was determined to be 100 mg/kg when delivered via IV dosing with a 20-fold safety margin. With no reported toxicity and with a shorter half-life, AVR-48 is able to reverse the worsening cardiopulmonary phenotype of experimental BPD and BPD-PH, compared to controls, thus positioning it as a future drug candidate.

Genetic Strain and Sex Differences in a Hyperoxia-Induced Mouse Model of Varying Severity of Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) is a disease prevalent in preterm babies with a need for supplemental oxygen, resulting in impaired lung development and dysregulated vascularization. Epidemiologic studies have shown that males are more prone to BPD and have a delayed recovery compared with females, for reasons unknown. Herein, we tried to recapitulate mild, moderate, and severe BPD, using two different strains of mice, in males and females: CD1 (outbred) and C57BL/6 (inbred). Aside from higher body weight in the CD1 strain, there were no other gross morphologic differences with respect to alveolar development between the two strains. With respect to lung morphology after oxygen exposure, females had less injury with better preservation of alveolar chord length and decreased alveolar protein leak and inflammatory cells in the bronchoalveolar lavage fluid. In addition, housekeeping genes, which are routinely used as loading controls, were expressed differently in males and females. In the BPD mouse model, gonadotropin-releasing hormone was increased in females compared with males. Specific miRNAs (miR-146 and miR-34a) were expressed differently in the sexes. In the severe BPD mouse model, administering miR-146 mimic to males attenuated lung damage, whereas administering miR-146 inhibitor to females increased pulmonary injury.

Inhibition of microRNA-451 is associated with increased expression of Macrophage Migration Inhibitory Factor and mitgation of the cardio-pulmonary phenotype in a murine model of Bronchopulmonary Dysplasia.

BACKGROUND: Macrophage migration inhibitory factor (MIF) has been implicated as a protective factor in the development of bronchopulmonary dysplasia (BPD) and is known to be regulated by MicroRNA-451 (miR-451). The aim of this study was to evaluate the role of miR-451 and the MIF signaling pathway in in vitro and in vivo models of BPD. METHODS: Studies were conducted in mouse lung endothelial cells (MLECs) exposed to hyperoxia and in a newborn mouse model of hyperoxia-induced BPD. Lung and cardiac morphometry as well as vascular markers were evaluated. RESULTS: Increased expression of miR-451 was noted in MLECs exposed to hyperoxia and in lungs of BPD mice. Administration of a miR-451 inhibitor to MLECs exposed to hyperoxia was associated with increased expression of MIF and decreased expression of angiopoietin (Ang) 2. Treatment with the miR-451 inhibitor was associated with improved lung morphometry indices, significant reduction in right ventricular hypertrophy, decreased mean arterial wall thickness and improvement in vascular density in BPD mice. Western blot analysis demonstrated preservation of MIF expression in BPD animals treated with a miR-451 inhibitor and increased expression of vascular endothelial growth factor-A (VEGF-A), Ang1, Ang2 and the Ang receptor, Tie2. CONCLUSION: We demonstrated that inhibition of miR-451 is associated with mitigation of the cardio-pulmonary phenotype, preservation of MIF expression and increased expression of several vascular growth factors.

Correction to: Inhibition of microRNA-451 is associated with increased expression of Macrophage Migration Inhibitory Factor and mitigation of the cardio-pulmonary phenotype in a murine model of Bronchopulmonary Dysplasia.

An amendment to this paper has been published and can be accessed via the original article.

Adiponectin deficiency induces mitochondrial dysfunction and promotes endothelial activation and pulmonary vascular injury.

Adiponectin (APN), an adipocyte-derived adipokine, has been shown to limit lung injury originating from endothelial cell (EC) damage. Previously we reported that obese mice with low circulatory APN levels exhibited pulmonary vascular endothelial dysfunction. This study was designed to investigate the cellular and molecular mechanisms underlying the pulmonary endothelium-dependent protective effects of APN. Our results demonstrated that in APN-/- mice, there was an inherent state of endothelium mitochondrial dysfunction that could contribute to endothelial activation and increased susceptibility to LPS-induced acute lung injury (ALI). We noted that APN-/- mice showed decreased expression of mitochondrial biogenesis regulatory protein peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) and its downstream proteins nuclear respiratory factor 1, transcription factor A, mitochondrial, and Sirtuin (Sirt)3 and Sirt1 expression in whole lungs and in freshly isolated lung ECs from these mice at baseline and subjected to LPS-induced ALI. We further showed that treating APN-/- mice with PGC-1α activator pyrroloquinoline quinone enhances mitochondrial biogenesis and function in lung endothelium and attenuation of ALI. These results suggest that the pulmonary endothelium-protective properties of APN are mediated, at least in part, by an enhancement of mitochondrial biogenesis through a mechanism involving PGC-1α activation.-Shah, D., Torres, C., Bhandari, V. Adiponectin deficiency induces mitochondrial dysfunction and promotes endothelial activation and pulmonary vascular injury.

Outcomes in COVID-19 Positive Neonates and Possibility of Viral Vertical Transmission: A Narrative Review.

OBJECTIVE: Novel coronavirus disease 2019 (COVID-19) seems to affect adults and pediatric patients differently. While neonates are a special population, little is known about the neonatal outcomes. This study aimed to investigate the outcomes in COVID-19 positive neonates and incidence of vertical transmission of the virus by reviewing available literature. STUDY DESIGN: This study is a narrative review of available literature on "COVID-19 in neonates," for which PubMed and Google Scholar were used to search the published articles. RESULTS: We summarized the data from 39 published studies that are comprised of 326 COVID-19 positive peripartum mothers with respective neonatal outcomes. Twenty-three neonates have been reported to be COVID-19 positive. Male neonates were affected significantly more (79%) than female neonates. Approximately 3% neonates acquired infection through suspected vertical transmission. Strict infection prevention measures during the perinatal time can significantly reduce the chance of horizontal transmission of the virus. Overall, neonates were asymptomatic or mildly symptomatic regardless of gestational age at birth and required only supportive measures. There was 0% mortality in COVID-19 positive neonates. CONCLUSION: From available published data to date, we can conclude that the prognosis of COVID-19 positive neonates is good with no mortality. There appears to be minimal vertical transmission of the infection. KEY POINTS: · Majority of COVID-19 positive neonates showed mild clinical signs and symptoms with no mortality.. · Most COVID-19 positive neonates require only supportive measures.. · Possibility of viral vertical transmission is very low..